Abstract
Abstract Using an atomistic shell model we study the temperature dependence of the ferroelectric properties of BaTiO 3 under biaxial compressive strain applicable to growth on perovskites substrate. Molecular dynamics simulations show a “ r → c → p ” sequence of phase transitions when temperature is increased, and the absence of an “ ac phase”. The first-order paraelectric-to-ferroelectric phase transition presents in bulk changes to a second-order one as a consequence of the in-plane constraint imposed by the mechanical boundary conditions. From the tetragonal ferroelectric c phase, the transition takes place in a finite range of temperature where the lattice parameter normal to the plane keeps approximately constant until T c is reached. Analysis of the local polarization behavior reveals an order–disorder dynamics as the dominant mechanism of the transition.
Highlights
Ferroelectric materials are attractive for device applications due to their ability to maintain a macroscopic polarization that can be switched by the application of an electric field.[1]
[3] For example, using molecular beam epitaxy and pulsed laser deposition, thin films of the prototypical ferroelectric perovskite BaTiO3 were biaxially grown on GdScO3 and on DyScO3; it was found that Tc and the remanent polarization were much higher than in bulk BaTiO3.[4]. It was shown that the phase-transition nature changes to second order with respect to the firstorder transition in the bulk crystal
One can clearly see that the fix in-plane strain mimicking a substrate replaces the four phases present in bulk BaTiO3 by the following three phases
Summary
Ferroelectric materials are attractive for device applications due to their ability to maintain a macroscopic polarization that can be switched by the application of an electric field.[1]. The first-order paraelectric to ferroelectric phase transition presents in bulk changes to a second-order one as a consequence of the in-plane constraint imposed by the mechanical boundary conditions.
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